4.0 Chugs and loses power occasionally

[ozziemo27]

My 99' 4.0 has 142,000 miles on it and every once ina while, say every 30 miles i seem to lose power and i have to give it more gas to come back up again as an example say if im going down the highway. Sometimes when im sitting idle it seems to chug and not idle right. I have never had any engine problems, is this an indication for more problems to come? what on earth is causing this?

 

[Mechanickid]

I have the exact same problem with my 94 4.0 but it has 168k on it.

 

[MountainMike]

That's a strange thing you got there Ozzie. Did you recently switch fuels or put in an additive? Or has it always done this? Maybe try a higher octane fuel and some injector cleaner. I'm running some cleaning V-Power through mine and noticed a perfomance increase. What grade do you run? I run regular but may switch as the 91 I'm burning now solved some odd noises and performance issues.

 

[ozziemo27]

I haven't changed anything, it started doing this maybe 250-300 miles ago, i just run regular, im going to buy some fuel injector cleaner as i havent run it in a few thousand miles... its so weird, on the way to class this morning, about 40 miles, it didnt happen once.... but it happened yesterday twice